1. Field of the Invention
This invention relates generally to apparatus and method for generating gaseous polyhydridic compounds of Group IV-VI elements, e.g., arsine, phosphine, silane, germane, hydrogen sulfide, hydrogen selenide, and hydrogen telluride, in situ, from solid precursor compounds therefor and also relates to the solid precursor compositions themselves.
2. Description of The Related Art
In the manufacture of semiconducting materials and semiconductor devices, various hazardous gaseous compounds containing elements from Groups IV-VI of the Periodic Table are widely employed.
Among the aforementioned hazardous gas compounds containing Group IV-VI consituent elements are the polyhydridic compounds set out below.
Group IV: silane, and germane. PA1 Group V: ammonia, phosphine, arsine, and stibine. PA1 Group VI: hydrogen sulfide, hydrogen selenide, and hydrogen telluride. PA1 (i) a reaction vessel containing a composition comprising a solid precursor compound for the polyhydridic compound, of the formula: EQU M.sub.x G.sub.y H.sub.z, PA1 wherein: M is a metal moiety selected from the group consisting of lithium, sodium, magnesium, zinc, potassium, aluminum, and intermetallic complexes and alloys thereof; x is a number having a value of from 1 to 3, inclusive; y is a number having a value of from 1 to 2, inclusive; and z is a number having a value of from 0 to 4; inclusive; PA1 (ii) a source of a fluid-phase protonic activator compound which is reactive with the precursor compound to yield as reaction product (a) the aforementioned polyhydridic compound and (b) a solid reaction product compound containing the metal moiety M; PA1 (iii) means for flowing the activator compound from the aforementioned source thereof to the reaction vessel containing the solid precursor compound for the polyhydridic compound, for reaction of said activator compound with the solid precursor compound to form the polyhydridic compound in the reaction vessel; and PA1 (iv) means for discharging the polyhydridic compound from the reaction vessel. PA1 (A) a solid precursor compound for the polyhydridic compound, of the formula: EQU M.sub.x G.sub.y H.sub.z, PA1 wherein: M is a metal moiety selected from the group consisting of lithium, sodium, magnesium, zinc, potassium, aluminum, and intermetallic complexes and alloys thereof; x is a number having a value of 1 to 3, inclusive; y is a number having a value of 1 to 2, inclusive; and z is a number having a value of 1 to 4, inclusive; with PA1 (B) a fluid-phase protonic activator compound to yield as reaction product (a) the aforementioned polyhydridic compound and (b) a solid reaction product compound containing the metal moiety M; and PA1 recovering the polyhydridic compound from the reaction.
The above-listed gaseous compounds are required in widely varying concentrations in semiconductor manufacturing plants, and at widely varying flow rates. As a result of toxicity and safety considerations, these hazardous gaseous compounds must be carefully handled in the semiconductor manufacturing facility.
In conventional practice, the aforementioned Group IV-VI gaseous compounds are provided in the semiconductor manufacturing plant in high pressure gas cylinders. Depending on the scale of the semiconductor manufacturing operation, the inventory of such high pressure gas cylinders typically is quite large. With such large inventories of high pressure gas cylinders, there is the associated danger of tank ruptures resulting in gross introduction of the hazardous gaseous compound to the environment in the manufacturing plant. There is also the danger, even more insidious, of leakages from such cylinders due to defects in or damage to the cylinder heads, gas flow regulators, and the like, which are a not infrequent occurence in instances where large numbers of high pressure gas cylinders are present.
In addition to the safety and toxicity considerations associated with the risk of undesired introduction of the Group IV-VI hazardous gas to the ambient air in the semiconductor plant, in instances where a multiplicity of high pressure gas cylinders are employed to supply the Group IV-VI gas, there are also the logistical difficulties involved in the storage and transport of large numbers of high pressure gas cylinders. Such gas cylinders are typically quite heavy, and thus are not easily moved or installed in the semiconductor manufacturing plant. Due to their bulky and unwieldy character, such gas cylinders typically require mechanical transport means to move same from place to place in the semiconductor manufacturing plant, and special mounts and retention structures typically are required to hold the cylinders in position when installed in the semiconductor manufacturing facility.
As an example of the foregoing considerations attendant the use of Group IV-VI hydridic compounds, arsine is currently indispensible in the fabrication of both compound (e.g., gallium arsenide) and silicon semiconductor devices.
Arsine is required in high concentrations for the preparation of compound semiconductors during the deposition process, as well as a large inventory of arsine for the maintenance of continuous operations. Such large arsine inventories are associated with a large number of high pressure arsine gas cylinders, since conventional gas cylinders generally contain from about 1 to 10 pounds of arsine (AsH.sub.3) per cylinder. See, for example, J. La Dou, "The Use of Toxic Gases in The Microelectronic Industry," presented at the STEP/SEMI program: Safety Aspects of Effluents From CVD Process Systems, May 23, 1986; and Western Fire chief's Association, Article 51, Uniform Fire Code, 1985 Addition, page 141.
On the other hand, in the manufacture of silicon-based semiconductor devices, arsine is employed as a dopant material at relatively low concentrations, on the order of from about 20 to about 100 parts per million. Even though used in dilute gas mixtures in such application, there remains the risk of a high pressure gas cylinder of arsine rupturing or leaking, and releasing all of the contained arsine into the surrounding environment in the manufacturing plant.
It would therefore be a significant advance in the art to provide arsine, as well as other hydridic Group IV-VI hydridic compounds, in a manner which avoids the difficulties and hazards attendant the use of high pressure gas cylinders containing such compounds.
Accordingly, it is an object of the present invention to provide an apparatus, method, and composition for generating polyhydridic gaseous compounds of Group IV-VI elements in situ, thereby obviating the need for bulk provision of such gaseous compounds in high pressure gas cylinders.
It is another object of the present invention to provide a solid precursor composition for in situ generation of polyhydridic compounds of Group IV-VI elements, which may be usefully employed to generate the desired gaseous compound on demand at purity levels consistent with the requirements of semiconductor manufacturing operations.
Other objects and advantages of the present invention will be more fully apparent from the ensuing disclosure and appended claims.